Weld wheel assembly for disposition on a membrane welding machine

ABSTRACT

A weld wheel assembly for disposition on a membrane welding machine, and for positioning a weld wheel adjacent a nozzle hot air outlet for pressing an overlying roof membrane heated by the nozzle against an underlying roof membrane heated by the nozzle, for welding the membranes together. The assembly includes a weld wheel rotatably mounted on an axle which is moveable toward and away from the membranes, and pressure exerting structure mounted on the machine and operable to bias the axle toward the membranes during operation of the machine.

CROSS-REFERENCE TO RELATED APPLICATION

This is a division of application Ser. No. 09/399,129, filed Sep. 20,1999 in the names of James Rubenacker et al.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a membrane welding machine having a nozzle fordirecting discrete streams of air along separated and parallel first andsecond paths, and is directed more particularly to a weld wheel assemblyfor a machine for heat welding two overlapping roof and/or waterproofingmembranes to each other.

2. Description of the Prior Art

It is known to provide a device for heat welding two overlapping roofmembranes to each other, and to provide such device with a nozzle fordirecting discrete streams of fluid along separated and parallel firstand second weld paths. See, for example, U.S. Pat. No. 4,834,828, issuedMay 28, 1989, to Colin R. R. Murphy.

The Murphy patent relates to a machine for effecting continuous heatwelds on either side of a fastener means, such as a row of fasteners, oran elongated bar. To effect the parallel welds simultaneously, theMurphy machine is provided with a nozzle which directs a stream of hotair to generally parallel paths on both sides of the fastener means. Theupper overlapping membrane is heat sealed to the lower overlappedmembrane along the overlap portion to seal the two membranes together oneither side of the fastener means. The fastener means fastens the lowermembrane to an uppermost hard surface of a roof, and is, in turn,covered by the upper membrane. To effect the two welds simultaneously,the nozzle is essentially a bifurcated nozzle which is moved by themachine between the two membranes, under an edge of the upper membrane.

The Murphy nozzle is provided with two outlets substantiallyside-by-side and in substantially the same plane, heightwise. The twooutlets are separated by a bridge portion which connects the two outletsand channels hot air thereto. It has been found that the nozzlearrangement is not entirely satisfactory in that the closeness of thetwo welding locations causes one to adversely influence the other. Ithas been found that air flows vary in intensity and temperature due tonozzle design. Further, hot air from one nozzle outlet crosses over tothe area impacted by the other nozzle outlet and causes bubbling orrippling of the upper membrane on the lower membrane. It has furtherbeen found that the two outlets, being in substantially the same plane,both tend to drag along the surface of the lower membrane and cause thenozzle bridge portion, i.e., the nozzle portion between the two outlets,to move along the fastener means with insufficient clearance. Stillfurther, because the Murphy nozzle outlets are in the same verticalplane, and weld simultaneously, the membranes tend to move, causingwrinkles. When the fastener means comprises a row of discrete fastenersor elements, the nozzle bridge portion is bounced upwardly uponencountering a fastener or element, causing the nozzle outlets to risemomentarily, effecting a non-welding segment in both weld paths andpotentially creating “fishmouths” in seams. The Murphy nozzle, wheninserted into the membrane overlays, is locked into position and cannotaccommodate irregularities in the substrate without diminishing seamquality.

There is thus a need for an improved nozzle of the type described above,but in which the welds are effected concurrently but at points removedfrom each other such that one weld contributes to another, rather thandetracting from the other, and in which the welds are effectedcontinuously and free from interruptions caused by collisions with thefastener means.

SUMMARY OF THE INVENTION

It is, therefore, an object of the invention to provide an improvednozzle for directing discrete streams of hot air along separated andparallel first and second paths.

A further object of the invention is to provide an improved nozzle for adevice for heat welding two overlapping roof membranes to each other,wherein a fastener means is disposed between the overlapping membranes.

With the above and other objects in view, as will hereinafter appear, afeature of the present invention is the provision of a nozzle fordirecting discrete streams of fluid along separated and generallyparallel first and second paths. The nozzle comprises a chamber forreceiving air of a selected temperature, a first outlet arm extendingfrom the chamber and having a first outlet at a distal end thereof andin a first outlet plane, and a second outlet arm extending from thechamber and having a first portion adjoining the chamber and having anaxis transverse to an axis of the first outlet arm, and having a secondportion with a second outlet at a distal end thereof and in a secondoutlet plane, an axis of the second portion being generally parallelwith the axis of the first outlet arm, the second outlet plane beingoffset from the first outlet plane.

In accordance with a further feature of the invention, there is provideda nozzle for a device for heat welding two overlapping roof membranes toeach other, wherein a fastener means is disposed between the overlappingroof membranes, and the nozzle is mounted on the device and adapted toeffect heat welds to the roof membranes on both sides of, and adjacentto, the fastener means. The nozzle comprises a tubular body defining achamber for receiving heated air, a first outlet arm extending from thebody and having a first outlet at a distal end thereof, a second outletarm extending from the body and having a first portion adjoining thechamber and having an axis transverse to an axis of the first outletarm, and having a second portion with a second outlet at a distal endthereof, an axis of the second portion being generally parallel with theaxis of the first outlet arm. The second outlet arm first portion isrecessed on an underside thereof so as to permit the fastener means topass therethrough as the device and the nozzle move along the paths.

In accordance with a further feature of the invention, there is provideda roof membrane welding assembly for heat welding two overlapping roofmembranes to each other, wherein a fastener means is disposed betweenthe overlapping roof membranes, the assembly being mounted on a deviceadapted to effect heat welds to the roof membrane on both sides of, andadjacent to, the fastener means. The welding assembly comprises a nozzleprovided with a chamber for receiving heated air, a first outlet armextending from the chamber and having a first outlet at a distal endthereof, a second outlet arm extending from the chamber and having asecond outlet at a distal end thereof, the first outlet being disposedin a first plane, and the second outlet being disposed in a second planeremoved from the first outlet plane. A first weld wheel is mounted onthe device adjacent to, and in operation immediately following, thenozzle first outlet. A second weld wheel is mounted on the deviceadjacent to, and in operation immediately following, the nozzle secondoutlet. One of the weld wheels is biased by biasing structure on thedevice toward the roof membrane in operation of the device.

In accordance with a still further feature of the invention there isprovided a weld wheel assembly for disposition on a roof membranewelding machine and for positioning a weld wheel adjacent a nozzle hotair outlet for pressing an overlying roof membrane heated by the nozzleagainst an underlying roof membrane heated by the nozzle, for weldingthe membranes together. The assembly comprises a weld wheel rotatablymounted on an axle which is moveable toward and away from the membranes,and pressure exerting structure mounted on the device and operable tobias the axle toward the membranes during operation of the machine.

The above and other features of the invention, including various noveldetails of construction and combinations of parts, will now be moreparticularly described with reference to the accompanying drawings andpointed out in the claims. It will be understood that the particulardevice embodying the invention is shown by way of illustration only andnot as a limitation of the invention. The principles and features ofthis invention may be employed in various and numerous embodimentswithout departing from the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference is made to the accompanying drawings in which is shown anillustrative embodiment of the invention, from which its novel featuresand advantages will be apparent.

In the drawings:

FIG. 1 is a perspective view of a prior art roof membrane weldingmachine;

FIG. 2 is a perspective view of a prior art nozzle of the type shown onthe machine of FIG. 1, and shown in a roof membrane welding operation;

FIG. 3 is a partially sectional and partially elevational view of themachine and nozzle of FIGS. 1 and 2 in operation;

FIG. 4 is a top planar view of one form of nozzle illustrative of anembodiment of the invention;

FIG. 5 is a rear elevational view of the nozzle of FIG. 4;

FIGS. 6 and 7 are side elevational views thereof; and

FIG. 8 is a bottom view of the nozzle of FIGS. 4-7 and a weld wheelassembly in place on a roof membrane welding machine.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1-3, it will be seen that a machine 10 on which theinvention finds particular utility comprises a frame 12 to which isfixed a handle 14 and on which are mounted wheels 16, includingindependent weld wheels 18. A hot air nozzle 20 is supported on theframe 12 and includes first and second outlets 22, 24 for directing twostreams of hot air in spaced, generally parallel paths. A housing 26 ismounted on the frame 12 for enclosing a motor and various electricalcomponents and controls (not shown).

The nozzle 20 is fixed to a heating element 28 which, in turn, is fixedto a blower 30 which is carried by the frame 12.

In operation, the nozzle 20 is positioned between roofing membranes Aand B (FIGS. 2 and 3) with the nozzle outlets 22, 24 on either side of afastener means F by which the membrane B is secured to a roof uppermosthard surface C. The fastener means F may comprise a batten bar 34, asshown in FIG. 2, or may comprise a series of discrete stress plates, asis known in the art. The motor in the housing 26 drives the machine 10in the direction of arrows D. The blower 30 forces air through theheating element 28 and through the nozzle 20. As the machine movesalong, jets of hot air from the nozzle 20 weld the membranes A and Btogether along opposite sides of the fastener means. Immediately afterthe hot air welds, the independent weld wheels 18 press the uppermembrane against the lower membrane to secure the membranes together. Adetailed description of the operation of the machine is provided in theaforementioned '828 patent.

Referring to FIGS. 4-7, it will be seen that the illustrative nozzle 40includes a tubular chamber 42 for receiving hot air at a selectedtemperature. The nozzle 40 further includes a hollow, generally flat,blade-like member 44 at a discharge end 46 of the chamber 42. The member44 extends from the discharge end 46 of the chamber 42 generally normalto an axis a—a of the chamber 42.

The member 44 includes a first outlet arm 48 extending from the end 46of the chamber 42, and having a first outlet 50 at a distal end 52thereof and disposed in a first outlet plane b—b (FIG. 4). The member 44further includes a second outlet arm 54 extending from the chamber 12and having a first portion 56 adjoining the chamber 42. An axis c—c(FIG. 4) of the first portion 56 extends transversely to an axis d—d ofthe first outlet arm 48. The second outlet arm 54 is provided with asecond portion 58 with a second outlet 60 at a distal end 62 thereof andin a second outlet plane e—e (FIG. 4). An axis f—f of the second portion58 is generally parallel with the axis d—d of the first outlet arm 48.The second outlet plane e—e is offset forwardly of the first outletplane b—b.

Referring to FIG. 5, it will be seen that the second outlet arm secondportion 58 is further removed from the chamber 42 in a direction of theaxis a—a of chamber 42, than is the first outlet arm 48. That is, inoperation, the second outlet arm second portion 58, including the secondoutlet 60, moves closer to the roof membranes than the first outlet arm48 and first outlet 50.

Referring still to FIG. 5, it will be seen that the first portion 56 ofthe second outlet arm 54 is provided on an underside 64 thereof with arecess 66 extending from a forward edge 68 (FIG. 4) of the second outletarm first portion 56 to a trailing edge 70 thereof. The recess 66 is acurved concavity with a mid-point 72 (FIG. 5) being most removed from abottom plane g—g of the second outlet arm second portion 58 and mostproximate an upper surface 74 of the second outlet arm first portion 56.

As may be seen in FIGS. 4 and 5, the first outlet arm 48 and firstoutlet 50 are substantially wider side-to-side than the second outletarm second portion 58 and second outlet 60.

Inasmuch as the configurations and dimensions of the nozzle outlets 50,60 are different, an air flow divider 76 (FIG. 4) is provided near thebottom of the chamber 42 in an area of transition to the first outletarm 48 and the second outlet arm portion 56. The disposition of thedivider 76 provides for substantially equivalent airflow through therespective outlets 50, 60. Substantially equal pre-heating of themembrane surfaces is accomplished by selected sizes and positions ofoutlet apertures 78 provided in the undersurfaces of the outlet arms 48,54 (FIG. 8), the apertures 78 extending in directions toward themembrane surfaces.

Referring to FIG. 8, it will be seen that the nozzle 40 is mounted on amachine 80 for heat welding two overlapping roof or waterproofingmembranes A, B, as described above, to effect heat welds to the roofmembranes on both sides of, and adjacent to, the fastener means F.

As in the machine 10 of FIGS. 1-3, the nozzle outlets 50, 60 are closelyfollowed in operation by weld wheels 82, 84. The nozzle first outlet 50is followed by a traditional weld wheel 82. However, because the spaceavailable between the nozzle second outlet 60 and an axle 86 for theweld wheel 82 is limited, the nozzle second outlet 60 is followed by aweld wheel 84 of a substantially smaller size than the weld wheel 82.Further, while a weight 88 (FIG. 8) may easily be added to the weldwheel 82, similar weights of correspondingly smaller size for the smallweld wheel 84 would have little impact on the pressing operation of theweld wheel 84. Still further, the position of the weld wheel 84 rendersthe placement of weights on the frame and directed toward the end ofpressing the wheel 84 downwardly in use, problematic.

To provide the desired downwardly directed force on the weld wheel 84,the wheel 84 is mounted on a spring-biased lever 90 which biases thewheel 84 toward the welded seam with a force substantially equal to theforce applied by the weld wheel 82.

In operation, the machine 80 is positioned relative to roof membranes Aand B substantially as shown in FIGS. 2 and 3 with respect to machine10. The heating element 28 and blower 30 are started by means well knownin the art, as are other known controls, sensors, and the like. Themachine 80 is moved along the roof membranes with the nozzle 40discharging two discrete streams of hot air, one from the outlet 50 andthe other from outlet 60. The two outlets 50, 60 effect sealssimultaneously in the sense that both eject hot air at the same time.However, the nozzle outlets 50, 60 effect seals at any given time alongtheir respective paths at points removed from each other, that is, in astaggered manner.

Referring to FIG. 8, it will be seen that as the machine 80 advances inthe direction D, the nozzle outlet 60 proceeds in advance of the nozzleoutlet 50. The weld wheel 84 follows immediately behind nozzle outlet60. Thus, the first weld (effected by outlet 60) is accomplished wellremoved from the second weld (effected by outlet 50), and the first weldand the pressure application thereto by weld wheel 84 is accomplishedwithout interference from the second weld hot air flow, resulting inbetter consistency and quality in the first weld. Further, inasmuch asthe first weld is pressure closed ahead of the second weld, the firstweld traps the hot air flowed in performance of the second weld in thevicinity of the second weld, such that hot air is retained in the secondweld area, improving second weld consistency and quality.

Referring to FIG. 5, it will be seen that the second outlet 60 isfurther removed from the chamber 42 than the first outlet 50, in adirection of the lengthwise axis a—a of the chamber 42. That is, inoperation, the second outlet 60 is lower, or closer to the membrane B,than the first outlet 50, and the first outlet 50 is higher, or furtherfrom the membrane B than the second outlet 60. Keeping in mind that thesecond outlet 60 moves ahead of the first outlet 50 in operation, hotair from the leading and lower second outlet 60 is able to movetransversely toward an area beneath the following and slightly raisedfirst outlet 50 to make a contribution to the weld of the first outlet50. Further, the slightly raised position of the first outlet 50 insuresthat the first outlet remains elevated relative to the second outlet 60and is positioned above the lower membrane even when the second outletdrags along the surface of the lower membrane B. During the course ofthe welding operation, the nozzle recess 66 always moves over thefastener means F, leading to uninterrupted welds of high quality andconsistency.

There is thus provided an improved nozzle for directing discrete streamsof hot air along first and second paths concurrently. There is furtherprovided such a nozzle for heat sealing two overlapping roof membranesto each other, wherein a fastener means is disposed between theoverlapping membranes. There is additionally provided a unique weldwheel arrangement which permits use of the above-described nozzle in aroof membrane welding machine.

It is to be understood that the present invention is by no means limitedto the particular construction herein disclosed and/or shown in thedrawings, but also comprises any modifications or equivalents within thescope of the claims.

What is claimed is:
 1. A weld wheel assembly for disposition on a roofmembrane welding machine and comprising first and second weld wheels fordisposition on opposite sides of an elongated fastening means andadjacent respective first and second nozzle hot air outlets and forpressing an overlying roof membrane heated by the nozzle outlets againstan underlying roof membrane heated by the nozzle outlets, for weldingthe membranes together on the opposite sides of the fastening means,said assembly comprising: a first weld wheel for following the firstnozzle outlet, said first weld wheel being of a weight sufficient toexercise a welding pressure on the membrane; and a second weld wheelrotatably mounted on an axle which is moveable toward and away from themembranes, said second weld wheel being of less weight than the weightof said first weld wheel; and pressure exerting structure mounted on themachine and operable to bias the axle toward the membranes duringoperation of the machine such that said second weld wheel is adapted forbiasing toward the membranes with a force substantially equal to a forceapplied by said first weld wheel.
 2. The weld wheel assembly inaccordance with claim 1 wherein said weld wheel assembly furthercomprises a lever pivotally mounted on the machine, and the axle ismounted on said lever.
 3. The weld wheel assembly in accordance withclaim 2 wherein said pressure exerting structure is operable to exertpressure on said lever to cause said lever to bias said second weldwheel toward the membranes.
 4. The weld wheel assembly in accordancewith claim 3 wherein said pressure exerting structure is a spring.